Pump

ABSTRACT

Pump, in particular a canned motor pump, to deliver liquids in water carrying domestic appliances and such like, which comprises a stator, a rotor and a drive shaft non-rotatably coupled to an impeller disposed in a pump compartment which is rotatably arranged inside a motor casing via bearing means wherein seal means are fitted on a first face end of the motor casing to seal said casing off against the pump compartment, wherein the bearing and seal means arranged on the first face end of the motor casing are in the form of a seal-bearing combination which comprises an axial bushing section for sliding arrangement on the drive shaft, a radial closing section to cover up the motor casing and at least one flexible seal element formed to said axial bushing section and/or said radial closing section.

This present invention relates to a pump, in particular a canned motorpump, to deliver liquids in water carrying domestic appliances or suchlike which comprises a stator, a rotor and a drive shaft non-rotatablycoupled to an impeller disposed in a pump compartment which is rotatablyarranged inside a motor casing via bearing means wherein seal means arefitted on a first face end of the casing to seal said casing against thepump compartment.

Prior known from DE 38 23 461 A1 is a pump for water carrying domesticappliances which comprises a motor casing with integrated stator androtor on the one hand and an impeller arranged outside said casing onthe other hand. The impeller shaft is firmly connected to a motor driveshaft which latter is via friction bearings arranged inside the motorcasing. A packing type special shaft seal fitted to an end shield of themotor casing is provided on a first face end of the motor casing to sealthe motor casing off against a pump compartment that is housing theimpeller.

DE 93 02 945 U1 is disclosing a pump having an electric motor and animpeller fixed to a drive shaft thereof wherein a rotor of the electricmotor is disposed inside a can (motor casing). The drive shaft is insliding arrangement via bearing bushes in the area of a first and secondface end of the can. A sealing collar is fitted to the first face endend of the motor casing to seal off said latter against a pumpcompartment housing the impeller. The bearing bushes need to be retainedin a separate bearing support. A drawback affecting this prior art pumpresides in that the extent of assembly work is relatively large withinthe area of the first face end of the motor casing that is facing thepump compartment.

It is an object of this present invention, therefore, to improve a pumpcomprising a drive shaft disposed inside a motor casing and an impellernon-rotatably connected to said drive shaft in such a way that theextent of assembly work needed to arrange the drive shaft and to sealoff the motor casing against the pump compartment is simply beingreduced.

To achieve this object the invention is in conjunction with the genericclause of Patent claim 1 characterized in that the bearing and sealmeans disposed on the first face end of the motor casing are integratedinto a seal-bearing combination which comprises an axial bushing sectionfor sliding arrangement on the drive shaft, a radial closing section tocover up the motor casing and at least one flexible seal element formedto said axial bushing section and/or said radial closing section.

The invention provides for a one-part seal-bearing combination whichserves both to support the drive shaft and to seal off the motor casingagainst a pump compartment. The one-part seal-bearing combination henceprovides in combination a number of sealing and bearing functions otherthan the multi- component solution that has been adopted in the art sofar. This affords the advantage that the extent of assembly work and/orassembly time can be reduced.

According to a preferred embodiment of the invention is the seal-bearingcombination provided with a radial closing section to the radial outermarginal edge of which a motor casing seal element is formed. This helpsto ensure dependable sealing action between motor casing and pumpcompartment. The motor casing seal element adjoins the closing sectionin radial direction and is preferably annular and of relatively smallradial thickness. This affords the advantage that it takes a relativelysmall quantity of material to provide a seal.

Another preferred embodiment of this present invention provides for theseal-bearing combination to have an axial bushing section to the axialend of which a shaft seal element is formed. Said shaft seal element issubstantially an axial extension of the bushing section and permits toachieve compact sealing of the motor casing in the area of the driveshaft.

According to the invention the closing section and/or the bushingsection is intended to serve as a carrier for seal means which aredisposed close to and distant from the centerline to achieve relativecompactness. The seal near the centerline (shaft seal element) and theseal means distant therefrom (motor casing seal element) are not directconnected, but just linked to each other via a disk of the closingsection to form a one-piece unit.

A modification of this present invention provides for the motor casingseal to be spray bonded to the bushing section and/or the closingsection of the seal-bearing combination. This permits seal means to befitted to a bearing in precise positions by easy methods.

Other advantages of this invention are as disclosed in the furthersubclaims.

One exemplary embodiment of the invention will now be described incloser detail with reference to the accompanying drawings.

In these drawings:

FIG. 1 is an axial section through a canned motor pump comprising anelectric motor and

FIG. 2 is a larger-scale axial section of a seal-bearing combinationdisposed in the area of the first face end of the motor casing that isfacing the pump compartment.

A pump according to an exemplary embodiment of this present invention asshown in the Figures is a canned motor pump 1 which can be preferablyused in water carrying domestic appliances such as a dishwasher or suchlike.

The motor casing of said pump 1 is a can 2 within which a rotor 3 of asynchronous motor and a drive shaft non-rotatably connected to saidrotor 3 are arranged. A not-shown stator of the synchronous motor may bedisposed outside said can 2.

The drive shaft 4 is non-rotatably connected to a pump impeller 6 thatis arranged in a pump compartment 5. Alternatively it is possible alsoto have the drive shaft 4 coupled to the pump impeller 6 in a free-wheelor rotational backlash mode.

A seal-bearing combination 8 having a bearing and sealing function isarranged in the area of a first face end 7 of the can 2 that is facingthe pump compartment 5. As will be seen more clearly from FIG. 2, theone-part seal-bearing combination 8 has an axial bushing section section9 for sliding arrangement of the drive shaft 4. This bushing section 9is made of the same material as another bushing section 10 that isintegral with the can 2 and by means of which the drive shaft 4 isslidingly arranged on said can 2 in the area of a second face end 11thereof.

The seal-bearing combination 8 moreover has a radial closing section 12to cover up an opening of the can 2. This closing section 12 is integralwith the bushing section 9 which it adjoins in a radially outwarddirection. Closing section 12 and bushing section 9 are made of anidentical plastic material. The can 2 also preferably consists of thatsame material as said sections 9 and 12.

Bushing section 9 and the further bushing section 10 provide a bearingmeans for the drive shaft 4 to be rotatably arranged in the motor casing(can 2). Said closing section 12 extending in radial direction of theseal-bearing combination 8 has a disk 13 from which a first lock ring 14protrudes on a side facing the motor casing 2. Said first lock ring 14serves to keep the seal-bearing combination 8 to the motor casing and/orcan 2 and is coaxial with the drive shaft 4 and/or with an axis A of thecan 2. The outer surface of the first lock ring 14 is in full contactwith an offset 15 of can 2.

A second lock ring 16 protrudes from the side of the disk 13 facing theimpeller 6 from which a shoulder ring 17 of the impeller 6 extends toform a labyrinth seal. This prevents undesirable ingress of threads andsuch like to the drive shaft 4. Said second lock ring 16 is coaxial withthe can 2 and/or the impeller 6.

The seal-bearing combination 8 is also provided with a flexible sealelement 18 arranged distant from the centerline as well as a flexibleseal element 19 close to it.

The seal element 18 distant from the centerline is a motor casing sealelement formed to a radial outer marginal edge 20 of the closing section12. The circular motor casing seal 18 is angular and comprises a firstleg 21 that extends from a periphery 22 of said radial outer marginaledge 20 of the closing section 12. This substantially provides sealingaction in radial direction.

The motor casing seal 18 is moreover provided with a second leg 23 thatextends from a radial surface 24 of the radial outer marginal edge 20 ofthe closing section 12, i.e. preferably on the side of the disk 13 thatis facing the impeller 6. This provides sealing action in axialdirection.

The sealing element 19 close to the centerline is a shaft seal formed toan axial end of the bushing section 10 preferably on a side of saidbushing section 9 that is facing the impeller 6. It serves to align thecan 2 relative to the pump compartment 5 in the area of the drive shaft4.

Motor casing seal 18 and shaft seal 19 are joined to the closing section12 and/or the bushing section 9 of the seal-bearing combination 8 byspray bonding. These seal means consist of identical elastic material,in particular an elastomer.

Motor casing seal 18 and shaft seal 19 are separated from each other andsubstantially extend within a radial plane E along which the disk 13 ofthe closing section 12 is disposed.

Both the motor casing seal 18 and the shaft seal 19 are of annularshape.

Closing section 12 and bushing section 9 are made of a rigid plasticmaterial which is suitable for the drive shaft 4 to be arranged in.

It goes without saying that the seal-bearing combination 8 is adaptedfor use in other types of pumps also.

The seal-bearing combination 8 is substantially for a bearing and asealing function, but may also perform a closing and/or joining functionwhich in this present exemplary embodiment is achieved by forming thelock rings 14 and 16.

1. A pump adapted to deliver liquids in water-carrying domesticappliances and such like, which comprises a stator, a rotor and a driveshaft non-rotatably coupled to an impeller disposed in a pumpcompartment which is rotatably arranged inside a motor casing viabearing means wherein seal means are fitted on a first face end of themotor casing to seal said casing off against the pump compartment,wherein the bearing and seal means arranged on the first face end (7) ofthe motor casing (2) are in the form of a seal-bearing combination (8)which comprises an axial bushing section (9) for sliding arrangement onthe drive shaft (4), a radial closing section (12) to cover up the motorcasing and at least one flexible seal element (18, 19) formed to saidradial closing section (12).
 2. The pump according to claim 1, whereinthe flexible seal element is a motor casing seal (18) formed to a radialouter marginal edge (20) of the closing section (12).
 3. The pumpaccording to claim 2, wherein the motor casing seal element (18) isannular.
 4. The pump according to claim 1, wherein the motor casing sealelement (18) is angular comprising two legs (21, 23) of which a firstleg (21) extends from the periphery (22) of the radial outer marginaledge 20 and a second leg (23) protrudes from a radial surface (24) ofthe radial outer marginal edge (20) of the closing section (12).
 5. Thepump according to claim 1, wherein the flexible seal element is a shaftseal (19) formed to an axial end of the bushing section (9).
 6. The pumpaccording to claim 5, wherein the shaft seal element (19) is formed tothe side of the bushing section (9) that is facing the impeller (6). 7.The pump according to claim 5, wherein the shaft seal (19) extending inaxial direction from the bushing section (9) is annular.
 8. The pumpaccording to claim 1, wherein the motor casing seal (18) and the shaftseal (19) are spray-bonded to the closing section (12) and/or thebushing section section (9).
 9. The pump according to claim 1, whereinthe motor casing seal (18) and the shaft seal (19) are made of anidentical elastic material, in particular an elastomer.
 10. The pumpaccording to claim 1, wherein the closing section (12) of theseal-bearing combination (8) comprises a disk (13) from which a firstlock ring (14) extends on the side facing the motor casing (2) forattachment to said casing (2) and a second lock ring (16) protrudes onthe side facing the impeller (6) for sealing connection with saidimpeller (6).